What mathematical instrument would you use to measure the height of a building? Explain in detail how you would use it (trig calculations)

Question

anonymous · Answer

..And its not tape measure!

anonymous · Answer

I believe what is important here for you to understand is the trigonometry. I can't tell you the instrument, because I've done no surveying. However, here's how the trigonometry would work:

You walk some distance away from the building, and you measure that distance. It looks like this:
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